1. Field of the Invention
The present invention relates to an image forming apparatus and image forming method for forming an image on a print medium.
2. Description of the Related Art
Various techniques have been proposed to suppress density nonuniformity caused by variations of printhead characteristics. For example, Japanese Patent Laid-Open No. 5-309874 discloses a technique of setting the number of multiscan operations in accordance with image data to be printed. According to this technique, a high-quality printed image can be obtained without unnecessarily decreasing the print speed.
Japanese Patent Laid-Open No. 2001-063015 discloses a technique of suppressing the print density of the first pass by setting the sum of the ratios of print amounts by odd-numbered scan operations smaller than that of the ratios of print amounts by even-numbered scan operations in a given print area.
Streaks (to be also referred to as streaking hereinafter) may appear in a printed image owing to variations of the orifice diameter, discharge direction, and the like of a printhead. If dots overlap each other within the same pass, streaks often appear more conspicuously than in a case where dots overlap each other in different passes, degrading the print quality. In multipass printing, as described in Japanese Patent Laid-Open No. 5-309874 and Japanese Patent Laid-Open No. 2001-063015, control using mask data and a density correction table cannot prevent overlapping of dots even at low image density. Density nonuniformity, streaking, and the like may stand out.